More confusion with Mr Malty

[CBMbrewer]

All I need to know is how to know what to set the yeast concentration Billion/ml and the non-yeast percentage when using the repitching from slurry tab.

I harvested about 2 months ago, washed and stored in the refrigerator.
I know how to use Mr Malty I just don't know what values to assume for those two parts.
Thanks in advance.

 

[Hammy71]

Being as the yeast is 2 months old, I'd err on the side of caution and keep the slider edged towards the non-yeast percentage. Just MHO.

 

[LLBeanJ]

I'd just go with the defaults. It will be close enough.

 

[tre9er]

All I need to know is how to know what to set the yeast concentration Billion/ml and the non-yeast percentage when using the repitching from slurry tab.

I harvested about 2 months ago, washed and stored in the refrigerator.
I know how to use Mr Malty I just don't know what values to assume for those two parts.
Thanks in advance.

I always set the yeast concentration to high, but remember this refers to the solids, not any liquid in the container. So if you have a beer/water layer on top and solid yeast layer on bottom, only pay attention to how much solid yeast you have. You'd only set it to a lower value if you had a thin slurry, ie. it hadn't settled yet and was all combined without much discernable layers.

The non-yeast percentage of well-washed yeast is going to be high. This refers to how much trub and/or hop matter you have in the solids. If you washed it well and it's very light in color, few if any chunks, it's *all* yeast.

A general rule is that 2b cells per ML are present for freshly harvested yeast and 1b cells/ML for yeast stored for more than a few weeks. Washing removes some non-yeast, but it also removes a lot of yeast. Recent experiments have shown that unwashed yeast contains about as many, if not more, viable cells as washed yeast.

 

[CBMbrewer]

I'd just go with the defaults. It will be close enough.

If I go with the defaults that would be 2.4 billion/ml. I understand that because I washed it it would be higher then that. If its up towards the 4.5 billion/ml thats almost twice as much. So if it is 4.5 billion/ml and not 2.4 I could be over pitching by a factor of 2. How will this be close enough?

 

[CBMbrewer]

I always set the yeast concentration to high, but remember this refers to the solids, not any liquid in the container. So if you have a beer/water layer on top and solid yeast layer on bottom, only pay attention to how much solid yeast you have. You'd only set it to a lower value if you had a thin slurry, ie. it hadn't settled yet and was all combined without much discernable layers.

The non-yeast percentage of well-washed yeast is going to be high. This refers to how much trub and/or hop matter you have in the solids. If you washed it well and it's very light in color, few if any chunks, it's *all* yeast.

Okay, so I am going to set the thickness to 3.5 billion/ml and the non-yeast percentage to 0 and the harvest date to 2 months ago and it gives me a 10% percent viability. Unfortunately I only have 10ml of this slurry. So 10 times 3.5 divided by the viability, so 10 leaves me with 3.5 billion cells. Should I just use that to plug into yeastcalc.com to see how many starters and how large to make?

 

[tre9er]

Okay, so I am going to set the thickness to 3.5 billion/ml and the non-yeast percentage to 0 and the harvest date to 2 months ago and it gives me a 10% percent viability. Unfortunately I only have 10ml of this slurry. So 10 times 3.5 divided by the viability, so 10 leaves me with 3.5 billion cells. Should I just use that to plug into yeastcalc.com to see how many starters and how large to make?

Yes. You should step them up for sure.

 

[LLBeanJ]

You probably will be overpitching, but overpitching is not nearly as critical an issue as underpitching is. Personally, I wouldn't worry about it, but if you're not comfortable with that and you think the yeast concentration should be set higher, set it higher, say to where it tells you that you need half as much as the defaults. Unless you're counting cells under a microscope, it's all a guestimate anyway.

Edit: just saw your latest post. Out of curiosity, based on your harvest date, what would have been your viable cell count if you went with the defaults, as per my recommendation?

 

[tre9er]

Interesting, I didn't know that Kai's results were now on yeastcalc. According to his numbers you should be fine with just a 2L starter or so...

 

[CBMbrewer]

Edit: just saw your latest post. Out of curiosity, based on your harvest date, what would have been your viable cell count if you went with the defaults, as per my recommendation?

Since I have 10ml and the default is 2.4 with a 10% viability I would have 2.4 billion cells. That's assuming a 0% non-yeast amount.

Interesting, I didn't know that Kai's results were now on yeastcalc. According to his numbers you should be fine with just a 2L starter or so...

I was hoping to use my other jar of washed yeast for another batch but since I don't have a lot I will use both. Giving me a total of about 25 ml so with 10% viability and 3.5 billion/ml I have 8.75 billion cells. Since I am brewing 5 gallons of 1.07 ale I need 2 starters of at least 1 gallon.
Where are you getting 2L from? If that is the case that would be much more convenient.

 

[tre9er]

Since I have 10ml and the default is 2.4 with a 10% viability I would have 2.4 billion cells. That's assuming a 0% non-yeast amount.



I was hoping to use my other jar of washed yeast for another batch but since I don't have a lot I will use both. Giving me a total of about 25 ml so with 10% viability and 3.5 billion/ml I have 8.75 billion cells. Since I am brewing 5 gallons of 1.07 ale I need 2 starters of at least 1 gallon.
Where are you getting 2L from? If that is the case that would be much more convenient.

stir plate? Using the K.Troester method, yeastcalc says a 2L stir-plate starter beginning with 8.75b cells would yield 290b cells, and you'd need 242 for 5g of 1.070 ale.

 

[CBMbrewer]

stir plate? Using the K.Troester method, yeastcalc says a 2L stir-plate starter beginning with 8.75b cells would yield 290b cells, and you'd need 242 for 5g of 1.070 ale.

Unfortunately I still do not have a stir plate. Now that I am harvesting, washing and reusing yeast I will have to buy/make one.

 

[tre9er]

See:

 

[LLBeanJ]

Since I have 10ml and the default is 2.4 with a 10% viability I would have 2.4 billion cells. That's assuming a 0% non-yeast amount.

So, with defaults it's ~2.4 billion viable cells and by adjusting the concentration slider away from default to 4.5, you end up with ~3.5 billion.

Now, go to yeastcalc and see what happens when you begin a starter with each of those numbers, with everything else being equal. What I think you'll see is that the end result cell count is very close, or as I might say, "close enough".

 

[tre9er]

Unfortunately I still do not have a stir plate. Now that I am harvesting, washing and reusing yeast I will have to buy/make one.

ACK! Man, make one from a CPU fan! It's hella easy and cheap! $15 or so!

Anyway, well yeah, then you need to step-up a few starters. 1.5 and 3L would be pretty damn close with intermittent swirling/shaking.

 

[tre9er]

So, with defaults it's ~2.4 billion viable cells and by adjusting the concentration slider away from default to 4.5, you end up with ~3.5 billion.

Now, go to yeastcalc and see what happens when you begin a starter with each of those numbers, with everything else being equal. What I think you'll see is that the end result cell count is very close, or as I might say, "close enough".

Difference is 37b cells after 2 stepped-up starters. Goes from needing a 1.5 and 3L starter to needing two 3L starters.

 

[CBMbrewer]

So, with defaults it's ~2.4 billion viable cells and by adjusting the concentration slider away from default to 4.5, you end up with ~3.5 billion.

Now, go to yeastcalc and see what happens when you begin a starter with each of those numbers, with everything else being equal. What I think you'll see is that the end result cell count is very close, or as I might say, "close enough".

Sounds good! I'm going to do one 2L with the "manual stir plate (swirl when I walk by)" then step up and do a biab for 3L, just so I don't feel like I'm pouring beer right down the drain.

ACK! Man, make one from a CPU fan! It's hella easy and cheap! $15 or so!

Yeah that's my plan. I was wondering if anyone had built one as a "carboy stir plate" to get enough slurry for a 10 gallon. Seems like it would be cool, maybe totally impractical though.

 

[LLBeanJ]

Difference is 37b cells after 2 stepped-up starters. Goes from needing a 1.5 and 3L starter to needing two 3L starters.

37 billion after two steps would be noise in my estimation. My point is that none of these numbers are exact. Is he sure he has 10 billion to start with? Maybe it's 7 or 13 or some other value. And does he use Kai's math or Jamil's for the starter step calculations? Why choose one over the other? Which one's right, since they can't both be right?

Unless we're counting cells under magnification, none of us really knows what we're starting with. As a result, most of us homebrewers are guestimating our starting cell counts when we reuse yeast (no matter how much we'd like to think otherwise). Even new vials and smack packs have a range of 70-130 billion actual cells. And since there are varying opinions (e.g., Kai and Jamil) on cell growth under certain conditions, we're even less sure of the end cell count.

That's why I say don't sweat it. Just give it a best guess, make a starter if that's what your guess dictates is needed, and brew. And in the end it will be fine.

 

[tre9er]

Sounds good! I'm going to do one 2L with the "manual stir plate (swirl when I walk by)" then step up and do a biab for 3L, just so I don't feel like I'm pouring beer right down the drain.

You can also pitch into less wort and then combine the unpitched wort together with it after 24-48 hours. For instance if you have half the needed cells, pitch into half the batch and keep the other half covered, using good sanitation practices, of course...then combine them after the lag phase is over.

http://woodlandbrew.blogspot.com/2012/12/no-more-wasteful-yeast-starters.html

 

[tre9er]

37 billion after two steps would be noise in my estimation. My point is that none of these numbers are exact. Is he sure he has 10 billion to start with? Maybe it's 7 or 13 or some other value. And does he use Kai's math or Jamil's for the starter step calculations? Why choose one over the other? Which one's right, since they can't both be right?

Unless we're counting cells under magnification, none of us really knows what we're starting with. As a result, most of us homebrewers are guestimating our starting cell counts when we reuse yeast (no matter how much we'd like to think otherwise). Even new vials and smack packs have a range of 70-130 billion actual cells. And since there are varying opinions (e.g., Kai and Jamil) on cell growth under certain conditions, we're even less sure of the end cell count.

That's why I say don't sweat it. Just give it a best guess, make a starter if that's what your guess dictates is needed, and brew. And in the end it will be fine.

Of course. That's what I do, too. I do my best to dial things in where I think they are and then check my results. I'd rather overpitch than underpitch in most cases, but not by a factor of 10. I think within a factor of 2 is great.

 

[LLBeanJ]

Sounds good! I'm going to do one 2L with the "manual stir plate (swirl when I walk by)" then step up and do a biab for 3L, just so I don't feel like I'm pouring beer right down the drain.

Sounds like a good plan to me.

 

[CBMbrewer]

Unless we're counting cells under magnification, none of us really knows what we're starting with. As a result, most of us homebrewers are guestimating our starting cell counts when we reuse yeast (no matter how much we'd like to think otherwise). Even new vials and smack packs have a range of 70-130 billion actual cells. And since there are varying opinions (e.g., Kai and Jamil) on cell growth under certain conditions, we're even less sure of the end cell count.

Very true. I guess I just want to be as close as I can.

using good sanitation practices, of course...

Damn, change of plans. Thought I had Star San solution, turns out its Sun Tan lotion

 

[el_caro]

Thought I had Star San solution, turns out its Sun Tan lotion

Lucky you caught that one in time or you would have ended up with a darker layer of yeast.